The present invention relates to a machine translation system for translating a sentence in one language to a sentence in another language.
Machine translation systems have been developed in recent years to translate an English sentence to a Japanese sentence, or vise versa. They, however, cannot perform a completely automatic translation. They can do nothing but assist the human translators.
Machine translation uses a dictionary as a data base. More specifically, the words and phrases of the object language, which are equivalent to those of the original language are retrieved from this dictionary. The retrieved words and phrases are reordered in accordance with the grammatical rules of the object language.
A sentences of the original language may be ambiguous for the following reasons. First, some words belong to two or more parts of speech. Secondly, a word or a phrase may modify two or more other sentence elements. Thirdly, a word or a phrase may have two or more equivalents of the object language. Hence, it is beyond the ability of the system to translate a sentence of the original language to a sentence of the object language which is generally considered to be appropriate.
When a plurality of translation possibilities are retrieved from the dictionary for each word or phrase of the original sentence, the operator (i.e., the human translator) selects one of them which he or she thinks is the most appropriate. That is, the operator and the system cooperate to translate sentences in the original language to those in the object language. This method is, so to speak, "interactive automatic translation." The interactive automatic translation has a drawback. When the same word or the same phrase, which has various equivalents of the object language, is used in the original many times, the operator must repeat the same selection many times. Therefore, the efficiency of an interactive automatic translation is low. Further, in order to select the most appropriate of the translation possibilities retrieved from the dictionary, the operator needs to understand the other words or phrases of the original language which seem to be associated with the word or phrase being translated. It takes him or her a considerable time to understand such other words and phrases. This also reduces the efficiency of the interactive automatic translation.